Process of etching printing forms for intaglio printing, planographic printing, and the like



Patented 23, 1930 1 UNITED STATES PATENT OFFICE \TUL1' U'B am, 0! BERLIN-BTEGIYIITZ, GERMANY, ASBIGHOB TO THE I131! DB. 3m &

GEEIIBCEE IABRIK G. B. H., 01' BEBLIN-LICHTEBFELDE, GERMANY rnocnss or n'rcm'ire ram'rme roams roa mraenro PRINTING, rnanooaarmc ramrmo, AND THE mxn Io Drawing. Application fled January 18, 1988, Serial Io. 383,527, and in Qermany January M, me.

In manufacturing printing forms for intag'lio printin planogra hie printing and the like by mechanical or photochemical processes, the procedure, as is known, ohas 'in' many cases. been to treat the forms covered with a developed copying layer with a suitable etching substance, e. g. with chloride of iron or nitric. acid or thelike. The ap plication of such etching substances on forms made of zinc, copper or the like is, however, connected with considerable difficulties, especially for this reason that the etching efect is easily carried too far, and that'under such circumstances also such parts of the plate or the like where etching is to be avoided may be affected.

I now have found that a perfectly satisfactory etching effect on such forms may be obtained if a mixture of chloride of iron and nitric acid is used as the etchin a ent and, preferably a' highly concentrate ch oride of iron solution in mixture with nitric acid, In this case the ironchloridemay previously be dissolved in a small-gluantity of water or may be mixed also in t e solid state with the nitric acid. It is also possible to use if desired, a special indifferent bearer for the etching agent in order to bring it in the form of a paste, salve or the like.

In the use of this'etchingagent the chloride of iron does not only assist in the etching of the printing plate or the like, but it also acts as a thickemng means for the nitric acid and in this way prevents a too far going effect of the nitric acid and an attacking 0 such arts of the plate which should not be I etche i. e. especially those that are yet covof increasing ered with the copying layer. "As has been proved, the same'efiect cannot be obtained with the same security by the use of other thickening means.

in iodide-of potasslum may be also added forthe purpose of cleansing the metal and ours.

In practicing-my invention it is' essential that a highly concentrated solution "of chloride of iron be used and that the nitric acid should .be present in the amount of 5% or on the exposed portions 0 'sisting in etching'said metal forms with a on t e exposed portions 0 its taking capacity forfat colforms for intag'lio printing,

further be added about 1 part of a solution .of iodine in iodide of potassium. The etching means thus prepared may be made to act, according to requirements, up to several minutes on the printing form covered with a developed copying layer, e. ,g. a developed chrome-gelatine ayer.

It is also within the meaning of the present invention to apply the process of etching according tothe invention to such printing forms as are provided with a layer of a resinous substance or of varnish. The action of the etching agent on the late or the like will in this case take place a er the development of the plate covered with the resinous solution, and before the. fatty colour is applied and before the treatment with alcohol.

Havin now particularly described and ascertaine the nature of my said invention, I declare that what I claim is '1. A process of etching metal printing forms for intaglio printing, planographic perililiting and the like said printing forms covered with a developed colloid layer the form, conmixture containing chloride of iron and nitric acid as the only essential ingredients. 2. A process of etching metal printing forms for intaglio' printing, rinting and the like said prmtin forms ein covered with a 'develo d collold layer 7 f the form, conaisting in etching said metal forms with a mixture of a solution containingat least of iron chlorideand at least 5% nitric acid.

" 3. A. process of etching metal printing planographic rinting and the like, said prmtin formsv ein coyered with a developed colloid layer planographic on t e exposed portions 'of the form, which.

comprises etching said metal formswith a mixture otchloride of iron, nitric acid and a solution of iodine in dissolved potassium iodide. w

4. A p of etching metal printing forms for intaglio printing, lanogmphic rinting and the li e said. pmntin forms in covered with a developed colloid loyer on .t e exposed portions of the form, which comprises etching said metal forms with a mixture of a highl concentrated solution of iron chloride, nitric acid and a. solution of iodine in dissolved potassium iodide.

In testimony whereof I have hereunto set my hand. v v m DR. JULIUS BEKK. 

